When conveying fluid, such as jet fuel, between interconnected conduits, it's highly advisable to provide electrical continuity between the interconnected conduits. Electrical continuity assures that there will be no build up of an electrostatic charge on a first conduit relative to the second interconnected adjacent conduit. As a result, a potential difference between the conduits or between a conduit and another reference surface is not created. It can be easily understood, that such a potential difference could give rise to an electrical spark and, in the presence of a vaporized fuel, the spark could cause the fuel to ignite.
Another requirement with aircraft fuel lines is that the seal provided by the coupling must be absolutely leak proof, and must be tightened in such a manner that it will not work loose in spite of vibrations or other internal or external forces to which it may be subjected.
A number of patents have proposed solutions to the problem of electrostatic charge build up. In U.S. Pat. No. 4,008,937 to Filippi, a coupling assembly is disclosed which is particularly adapted for use with fluid conveying lines. The coupling assembly includes an electrical jumper externally mounted thereon to minimize electrical charge build up and reduce the hazard of an electrical spark.
In U.S. Pat. No. 3,891,291 to Nadsady et al. a tubular coupling is disclosed which incorporates an electrical or bonding jumper. The bonding jumper includes an elongated leaf spring having undulations and made to fit wholly inside a retainer section. The leaf spring may include lateral projections which are wedged into locking engagement with side flanges within the retainer section. The leaf spring provides electrical contact between ferrules and fluid conveying tubular members.
In U.S. Pat. No. 3,999,825 to Cannon a tubular coupling assembly is disclosed which comprises a pair of retainer sections. Each of the retainer sections has a groove formed therein for containing a U-shaped conducting wire.
In U.S. Pat. No. 4,346,428 to Gale discloses a bonding jumper having a body portion and a pair of arms fixed to opposite ends of the body portion. The arms extend in opposite directions so that each arm contacts one of the annular flanges connected to each conduit member and a torque is produced tending to force the other arm into secure electrical contact with its contacted flange.
In U.S. Pat. No 4,487,462 to Gale et al. a pair of bonding jumpers are provided which each include an annular ring having a plurality of bonding jumper contact flanges at the inner edge which engages a surface of the flanges of the threaded coupling and a plurality of spaced retaining tangs at the outer edge which snap into a retaining groove in the coupler and the nut. The nut also includes a plurality of circumferentially spaced coupler contact tangs which are interspersed with the retaining tangs and contact the outer end of the coupler beyond the threads. While each of these devices work satisfactorily for its intended purpose of providing electrical bonding, none of them releasably lock the coupling to prevent uncoupling.
U.S. Pat. No. 3,669,472 to Nadsady discloses a coupling having an annular ring with spring fingers which releasably engage notches on the edge of a male connector to minimize the chance of the coupling becoming unthreaded due to vibrations or other forces on the coupling. In this device a separate releasable bonding ring is provided between the two coupling elements. A similar device is shown in British Pat. No. 1,046,601 to Marriette. French Pat. No. 692,067 to Bazinet discloses a washer having a spring finger which releasably engages a scalloped portion of a nut to releasably hold it in a fixed locked position. None of these patents disclose the use of the releasable locking means as a bonding jumper.
U.S. Pat. No. 2,890,434 to Ray et al., U.S. Pat. No. 3,753,205 to Tuger, U.S. Pat. No. 3,891,290 to Marshall and U.S. Pat. No. 4,285,564 to Spinner each disclose other forms of electrical bonding connectors to minimize the build-up of electrical charge from one pipe or conduit section to the next.